R: [R] weighting observations

[Federico Spinazzi]

>Functions that handle probability weights and frequency weights (I think
>the latter is what you want) are on my To Do list, but they are a long way
>off so it would be great if someone else were to handle them.
>
I never wrote a package for R, but I'm quite fluent in other programming
languages.
Even if I don't use R from much time I think I can help.
I basically need two kind of things:
- understand well how weights works (for example with categorical variables)
and what statistics are affected when weighting observations (I think all)
and how to deal with standard computations (for example how to perform a
cluster analysis on weighted data, how to do a regression ?) i.e.: the
identification of the domain of weights
- a better understanding of the Object-Oriented approach of R.

If someone could help me in some way with the first point I surely could
help (even on a single, well defined part of that domain).

>My preference would be for a function that accepted a weight= argument,
>since you might need more than one set of weights in a data frame
>(admittedly in somewhat unusual circumstances), and you might want to
>ignore the weights sometimes. You could have it both ways: have, say,
>attr(,"weights") on the data frame be the name of the column of weights
>and have the function use this by default if it is present.

Federico Spinazzi
spinazzi at databankgroup.it
Databank S.P.A
Via Spartaco, 19, ITALY
Tel. + 39 02 55002251




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